There's absolutely nothing remarkable about Jacob Hunter that occurred while he was a child. He was the middle one of three brothers, not one of which he has seen since he was 24. After high school he enlisted in the U.S. Marine Corps as an infantryman, his first orders taking him to 1st MarDiv in Camp Pendleton. He ended up being deployed all the time, seeing the world, getting drunk, getting in fights, getting in trouble, screwing lots of girls both foreign and domestic, and in spite of all that getting promoted.
At age 22 he re-enlisted as a Corporal and got to go to Scout Sniper School. His scores got him trained as a spotter, and he ended up being transferred to an infantry unit with 2nd MarDiv out of Camp Lejeune. More deployments. More Operations Other Than War. Another enlistment winding down, and Jake was thinking he'd go for a third enlistment until he got knocked down from sergeant to private for a drunk driving incident. In today's military the paperwork from a mistake like that will follow you forever. He just decided to quit.
Civilian life wouldn't work for Jake. It wasn't the discipline and the uniform wearing he missed. Truth to tell he couldn't stand that uniform bullshit and was never a particularly squared-away Marine. It was the excitement. The kicking in doors and hiding in the countryside for days waiting for someone to drive by so you could shoot them. The port calls overseas where you got to party and see new things, learn a few words of a new language, etc. These things just didn't happen in civilian life.
Knowing his paperwork would follow him into any branch he signed up with in the States, Jake got a lark of an idea and a plane ticket to France where he signed up in Castelnaudary for five years of service in the French Foreign Legion. His prior training helped him quite a bit, although his utter lack of how to speak French was a bit of a chore. Jake never thought of himself as much of a linguist, but immersion does wonders.
Opportunities opened up for a well-trained man with a clean slate in the Legion. Strictly by chance he found himself assigned to a post that hosted a foreign instructor in helicopter piloting, and Jake talked his way into groundschool for it with the understanding that he wouldn't be flying because he was enlisted. Like any student with an actual interest, he did well at it…well enough for one of the instructors to take notice and pull some strings, and get him to fly.
That instructor's name was Fedor, and he was an ex-Soviet pilot with a love for teaching that seemed not only to welcome Jake's interest in learning to fly, but nurtured it. Jake would've been an able student anyway, but having an able teacher only helped him along. They soon developed a closer working relationship than any of the other flight students did with their instructors, although that could easily have been because Jake was especially fortunate to even have one willing to get him behind the stick of an aircraft.
As with every flight student they had to rotate instructors for airtime. And as with every situation some people just don't like each other. More than a few of the other instructors resented having to spend any time at all on this enlisted guy who should never have been in the air anyway, and one day Jake got just one of those instructors as he went up for what should have been a routine flight. The helicopter was an old bird too obselete to be used in actual service, and maintenanced only as much as it was needed to keep it taking off and landing within safety specs. On his preflight checklist Jake noted an problem with the engine coolant on the helicopter but the instructor insisted it was nothing. Take off anyway.
Any other student might have been taken seriously. Though it occurred to Jake to put his foot down and refuse to fly until the problem was taken care of, he decided not to agitate the instructor and did what he was told. About five minutes into their flight path the engine overheated and smoke started issuing from the aircraft. Panicking, the instructor insisted on taking the controls and did so, Jake taking his hands off of the stick immediately. An emergency landing was attempted but the helicopter was doomed just fifty feet from the ground as it listed and flew to pieces from the rotors shattering on the earth.
The crash was immediately followed by a fire caused by leftover fuel, but by the time the rescue crew arrived they were amazed to find one thoroughly dead (but unburnt) flight instructor who was dragged from the crash site by one flight student named Jake who didn't have a scratch on him. Jake had no explanation for how he survived uninjured. He remembered being slammed around, having the console clamped down on him as the cockpit buckled on impact. He remembered even a piece of flying debris bouncing off of his ribcage in the chaos. All the time all he could think of was that you couldn't pull a needle out of his asshole, he was so freaked out.
Jake was questioned for the loss of the aircraft that resulted in the death of an instructor, and he told the truth about the whole business. Fortunately for him the evidence backed up what he said and Fedor backed him up too. Even Fedor know that instructor wasn't a particularly good one.
Little else of note happened in Jake's service with the Legion, at least that anyone else knew about. In secret he determined to get to the bottom of why he survived that crash. The puzzle didn't start to resolve itself until he got a knife jabbed in his gut one day by a drunken Australian sailor spoiling for a fight. Jake thought he just couldn't feel the stab wound, but after he beat the hell out of that sailor he realized he felt like he was superhumanly strong or something. And the knife not only did not harm him but failed even to puncture his shirt. Experimenting later only determined that Jake was not in fact invulnerable and could prick himself with a needle if he tried. It really confused him. Why not a helicopter crash or a knife to the gut, but needles or razors? Was it because he was only invulnerable to what other people did to him?
Eventually he learned that it was the tensing up that did it. Not only would Jake become almost invulnerable to trauma just by tensing his body, he also became stronger and heavier at the same time. His body became superdense and took anything he was wearing on him into that state at the same time. Experimenting with a bathroom scale he accidentally found he could go the other direction and become superlight as well, but after losing his balance and breaking his arm on a toilet seat of all things he found out just how dangerous being LESS dense than normal could be.
When Jake's five years of service ended he considered re-enlisting, but instead bid farewell to the Legion. He was getting tired of taking orders from politicians, and knew one man out there that somewhat shared that viewpoint. So it was he looked up Fedor, now going by the name Fedor Ibragimov. Fedor owned a company called Chicago Air, and Jake found himself welcomed with opened arms into his old teacher's employ.
When he confided in Fedor what he could do, why he survived that crash in North Africa, it opened some eyes. Because Fedor had a secret too that he shared in turn. Now Jake Hunter works for Ibragimov, but it's the best job he's ever had in the world. He gets to use his training and expertise doing things that nobody else would ever be allowed to do, and he also gets about as much time off as any guy could ever want. It's more like being a fulltime mercenary on retainer. Life is good.